Grinding apparatus



July 24, 1956 H. G. LUX 2,755,601

GRINDING APPARATUS Filed Sept. so, 1953 2 Sheets-Sheet 1 INVENTOR 17AM! yaw/4M1 (0 ATTORNEY July 24, 1956 H. e. LUX 2,755,601

GRINDING APPARATUS Filed Sept. 30, 1953 2 Sheets-Sheet 2 INVENTOR A A/w' q'aivrmawu/ ATTORNEY States Patent c 2,755,601 Patented July 24, 1956 GRING APPARATUS Hans Giinther Lux, Linz, Austria Application September 30, 1953, Serial No. 383,234

Claims. (Cl. 5172) This invention relates to grinding apparatus.

With the conventional grinding apparatus and the previous methods of grinding it was not possible to observe during the grinding operation the surface ground upon. This led to the formation of new grinding planes after each lifting of the article to be ground from the grinding wheel, for cooling or inspection, and thus to inaccurate surfaces ground, which are of poor appearance.

To overcome these disadvantages grinding apparatus has been disclosed which comprises a grinding wheel having a working end face and a face facing off said end face, said wheel being formed with stroboscopic apertures through both said faces, and means for rotating said grinding wheel at a speed sufficient to render visible through said apertures from the side of the grinding wheel where said face facing off said Working face is disposed a workpiece when contacting said working face. In this specification and the appended claims the term stroboscopic apertures refers to apertures enabling the wheel formed with them to produce said stroboscopic effect when driven by said means. It is known that an article behind a rotating apertured disk becomes distinctly visible from a certain rotary speed up. Hence stroboscopic grinding apparatus enables the observation of the surface ground upon during the grinding operation, e. g., to determine the correct time when the grinding operation is to be terminated, or the correct grinding angle. Moreover, when the article has been lifted, e. g. for cooling, it can be returned to its original position relative to the grinding wheel.

This invention relates more particularly to various improvements in stroboscopic grinding apparatus.

It is a first object of the invention to provide stroboscopic grinding apparatus in which the workpiece is substantially uniformly visible through the grinding wheel at several contact circles describable by a workpiece on the working face of the rotating grinding wheel.

It is a second object of the invention to provide stroboscopic grinding apparatus which prevents dazzling and irritation of the operator by a light source employed to illuminate the workpiece.

It is a third object of the invention to provide stroboscopic grinding apparatus which ensures an illumination of the workpiece throughout the apertured area of the working face by a light source, while avoiding excessive aperturing of the grinding wheel.

It is a fourth object of the invention to provide stroboscopic grinding apparatus having a grinding wheel for grinding selectively in a horizontal position, 'e. g. on its lower end face, and in a vertical position, e. g. on its rim, while utilizing the stroboscopic effect and illumination of the workpiece by a light source.

It is a fifth object of the invention to provide stroboscopic grinding apparatus having a grinding wheel for grinding selectively on its end face and on its rim, while utilizing the stroboscopic effect and illumination of the workpiece by a light source.

One feature of the invention resides in the arrangement of stroboscopic apertures in the grinding wheel so as to have along several contact circles describable by the workpiece on the working face of the rotating grinding wheel the same total width relative to the circumference of the circle.

Other features and objects of the invention will become apparent as the specification proceeds.

Another improvement in the previously known grinding apparatus resides according to the invention in the fact that the side faces at least of part of the slot-shaped apertures, or the axes and side faces at least of part of the hole-shaped apertures, are inclined towards the end faces of the plate-shaped grinding wheel, or to the peripheral surface of the pot-shaped grinding wheel. Hence the side faces of the slots or the axes and side faces of the holes are no longer normal but oblique relative to the respective working or peripheral surface of the wheel. As a result the latter has a propeller-like effect, producing a strong air stream or swirl, and thus provides an auto matic cooling, so that special water cooling measures can be eliminated in many cases. According to a further suggestion of the invention that effect can be be achieved or increased by arranging at the end face of the grinding wheel facing the operators eye a corotating wheel, which is similarly slotted, whereas its tongues remaining between the slots are bent in the form of propeller blades. When rotating the propeller wheel produces an intensified air stream through the slots or holes of the grinding wheel, suitably in a direction from the operator to the work, whereby burning of the cutting edges is prevented even without additional cooling measures. Obviously the width of the slots or holes, and the inclination of the side faces of the slots or axes and side faces of the holes must be chosen so as to ensure the view through the wheel.

According to the invention the apertures may consist of holes, the axis of each of which lies on the cylinder which is concentric with the wheel and tangential to the radially adjacent holes, and the wheel preferably is held in a similarly apertured carrier. Thereby it is achieved that the wheel can be looked through evenly at all parts thereof and any catching or bumping of radial slots, as might occur at insufiicient speeds, is safely prevented.

A particularly suitable construction of the grinding apparatus according to the invention provides for the illumination of the workpiece by a beam of light directed through the apertures of the wheel onto the workpiece surface ground upon, and reflected by said surface towards the operators eye. If desired, one or several lenses or the like may be inserted into the path of rays. This arrangement makes the area where material is being removed distinctly flicker in the form of schlieren, in a striking contrast against the parts not contacted by the grinding wheel. Any change of the grinding angle is recognized immediately by the dislocation of the streaky flicker, and can be corrected immediately. On the other hand, an alteration of the grinding angle will move the part where material is being removed, indicated by the flicker, to the point desired. With the aid of the lenses the image of the workpiece part ground upon can be magnified for most precise grinding work.

To render prominently visible only the surface part ground upon, which is illuminated through the apertures, and to prevent any dazzling and irritation of the operator by light rays that may be reflected by the end face of the grinding wheel, the invention further suggests to give a dull black finish at least to that part of the wheel body which lies between the apertures, on the side facing the eye. A particularly favorable construction of the lighting fixture, which also prevents dazzling, comprises a light source arranged a short distance apart from the end face of the wheel close to the wheel shaft, and covered toward the outside by a shade which extends as far as the slotted part of the wheel end face.

In a development of the invention the end faces of the slot-shaped apertures of the wheel intersect with the wheel axis at an oblique angle. This means that during rotation they describe a cone about the wheel axis. With the type of illumination described, the light rays obviously must impinge obliquely to the wheel end face from the side of the wheel axis in the longitudinal direction of the slot because perpendicular or almost perpendicular incidence would not give a useful reflection. For this reason the slot end faces are also given a corresponding inclination. This is possible without difliculty because with slot end faces normal to the wheel end face the innermost part of the slot would remain without illumination in any case so that this region of the wheel could not be used for the work. By this inclination of the slot end faces the apertures are reduced in size, the strength of the wheel is increased, and the danger of an undesired vibration of the wheel is diminished.

Further the grinding wheel is carried so that it can be moved pivotally and set on a horizontal axis parallel to its end faces. This enables the use of the wheel in a horizontal position, e. g. for surface grinding at the underside of the wheel, with observation from above, as well as in the usual vertical position, e. g. for grinding at the periphery of the wheel, with inclined observation from the side. In this connection the wheel advantageously is pivotally movable or tiltable about its horizontal tangent which is at the bottom when the wheel is in vertical position, because then the grinding operation can be performed at an unchanged level in both wheel positions. Hence no height adjustment of the hand rest or workpiece guide is required.

A particularly simple and suitable construction of the grinding apparatus, following the above principle, is obtained by providing an electric motor which is pivotally movable and can be set on a horizontal axis intersecting the motor shaft at the middle thereof, said motor shaft carrying a grinding wheel floating on each of its two extended ends. In that arrangement a protective cover is provided for each grinding'wheel so as to cover the wheel at its end facing the motor and on its periphery, while leaving free two wheel segments which when the wheel and motor axis is horizontal lie at the front and lower parts of the wheel, respectively. Adjacent to the segments left free, that cover incorporates two lamps in its portion arranged between the motor and the wheel. For grinding at the periphery of the wheel, the operator stands in front of the wheel end face remote from the motor and holds the workpiece against the lower periphcry of the wheel so that the light of the lower lamp arranged behind the end of the wheel facing the motor falls just on the area ground upon and is reflected by it to the operators eye. For surface grinding the motor is tilted through 90 deg. so that the grinding wheel is horizontal and below the motor. Now the operator stands in front of the wheel in the direction of the pivotal axis of the motor and holds the workpiece against the end face of the wheel from below, the light of the other lamp falling through the slots in the wheel on the workpiece from above and being reflected too. Hence the protective cover does not serve merely for protection against wheel particles flying off, sparks, etc., but at the same time forms the lamp casing and light shade. Obviously the protective cover might leave free only one wheel segment and in corporate only one lamp. In that case the protective cover may be arranged for rotation about the axis of the motor and wheel and lockable in any angular position desired. Then both types of grinding can be performed too.

Preferably two short rod-type or tubular lamps are arranged at right angles to each other, for optimum illumination. For an easy insertion and replacement of the lamps, each tubular lamp is inserted in a sleeve apertured at one end face for the passage of one contact pin of the lamp, which is urged by a spring or the like against that end face. Said sleeve is slidable like a cartridge into and can be fixed in bores of the protective cover, which bores are laterally open towards the end face of the wheel adjacent to the segments left open, whereas a contact is embedded in the bottom of the bore and the second terminal is preferably connected to ground. The sleeve has a window registering with the lateral opening of the bowl.

In the accompanying drawings the subject of the invention is shown by way of example.

Fig. l is an elevation of a plate wheel with simple radial slots.

Figs. 2, 3 and 4 are a perspective view and sectional views taken on lines lIllII and IVIV of Fig. 2, respectively and show a slotted plate wheel with inclined slots.

Fig. 5 is a fragmentary sectional view of a pot-shaped wheel.

Figs. 6 and 7 are in elevation and a cross-sectional view, respectively, of a grinding wheel having holes.

Fig. 8 is a perspective view of a grinding wheel with an additional propeller wheel.

Fig. 9 shows a wheel with slots of different inclination.

Figs. 10 and ll are an end view and side view, respectively, showing an entire grinding apparatus, and

Figs. 12-14 show a protective cover with lighting fixture in an elevation seen from the side facing the motor, in a horizontal sectional view, and in a front view, respectively.

A plate wheel 1 has radial slots 2, which during the rotation of the wheel enable the view therethrough to the workpiece disposed behind the wheel. For a uniform view through the wheel the slots 2 are of different lengths so that at the circumference of any concentric circle the same ratio exists between apertured surface area and working surface area. As may be seen from Figs. 2 and 4, the side walls of the slot-shaped apertures 2 of the plate-shaped grinding wheel 1 may be inclined relative to the end faces of the grinding wheel. Likewise the end faces 3 of the slot-shaped apertures 2 may be oblique, intersecting the axis of the wheel oliquely and forming during rotation a cone about the wheel axis. Similarly the side walls of slots 2a in the pot wheel 1a, shown in Fig. 5, are also oblique relative to the peripheral surface of the wheel.

According to Figs. 6 and 7 a plate wheel 1b has holes 4. The axis of each hole is disposed on the cylinder which is concentric with the wheel and tangential to the two adjacent holes. Thus the holes 4 lie on a spiral and are spaced thereon to have along several contact circles describable by the workpiece on the working face of the rotating grinding wheel the same total width relative to the circumference of the circle. The wheel 1b itself is held in a similarly apertured carrier 5.

Fig. 8 shows a corotating second wheel 6, which is arranged at the end face of the wheel 1 and is slotted too whereas its tongues remaining between the slots are bent like propeller blades whereby its rotation will produce a strong air stream through the slots 2 of the grinding wheel to provide cooling air during grinding. According to Fig. 9 the plate wheel 1 has slots 2 normal to the end faces, and to the left and right thereof has slots 2a, 2b of mutually opposite inclination. The inclination and spacing of slots 2a, 2b are so chosen that in the case of a normal distance of the eyes each eye can see through one slot.

As shown in Figs. 10 and 1f, the entire arrangement according to the invention comprises an electric motor 7, which is carried by a trunnion 9 held in a bracket 8, in which it can be rotated and clamped fast. Two plate wheels 1 are mounted in a cantilever arrangement on the shaft 10 of the electric motor 17, which shaft is extended at both ends. The position of the wheel and motor and the most suitable type of illumination is shown at the left in Fig. for peripheral grinding, and with dash lines in Fig. 11 for surface grinding.

It is apparent that the shaft 10 is supported only on one side of each wheel 1 and that the light source 12 is arranged adjacent to the end face of the wheel on the side where the shaft 10 is supported.

A protective cover 11 is screwed to the motor for each wheel 1. The cover covers the wheel toward the motor and on the periphery while leaving free two wheel segments, which when the motor axis is in the horizontal position shown are at the front and lower parts of the wheel. in the portion arranged between wheel and motor the cover incorporates two rod-type lamps 12, 13, which are inserted in a sleeve 14, which has an end face apertured for the passage of one contact pin of the lamp and has a corresponding window 15. In the sleeve 14, the lamps 12, 13 are urged by a spring 16 against the apertured end face. The protective cover 11 is formed with two mutually orthogonal bores 17, which are open adjacent to the segments left free and in which the sleeves 14 can be inserted like cartridges. At the bottom of the bore a contact 18 is embedded, whereas the second terminal of each lamp is connected to ground. The protective cover carries at its front a slotted bearing hole 19, in which the pivot pin 29 of a hand rest 21 is carried and can be fixed by clamping.

From Figs. 12 and 13 it is apparent that the source of light 12 is arranged radially inwardly of the inner ends of slots 2, which have end faces lying on an imaginary cone coaxial with wheel 1 and tapering toward the side of the wheel opposite to said light source to expose the entire slot area of the working rim face to the light from said source and to observation from the side of the wheel opposite to said light source while shielding the side of the wheel opposite to said light source from direct light from said source.

I claim:

1. In grinding apparatus, the combination of an electric motor having a shaft and arranged with freedom of pivotal movement on a horizontal axis normal to and intersecting said shaft at the middle thereof, means operable to lock said motor in any of at least two angular positions, including the position in which said shaft is vertical and the position in which said shaft is horizontal, said shaft having two extensions at opposite ends of the motor, and two grinding wheels each of which is carried on one of said extensions in a cantilever arrangement and has a working face and a face opposite said working face, said wheels being formed with stroboscopic apertures through both said faces, said motor constituting means for rotating said grinding wheels at a speed sufficient to render visible through said apertures of each wheel from its side where said face opposite its working face is disposed a workpiece contacting its working face, and means for directing a beam of light through said apertures of each wheel onto the workpiece for reflection by the workpiece toward the side of the wheel having said face opposite said working face, said last-named means comprising at least one lamp disposed between said wheel and said motor, said lamp being secured for concurrent movement with said shaft whereby it is in the same position relative to said wheel for every position of said shaft.

2. In grinding apparatus, the combination of an electric motor having a shaft and arranged with freedom of pivotal movement on a horizontal axis normal to said shaft, means operable to lock said motor in any of at least two angular positions, in one of which said shaft is horizontal, a grinding wheel carried by said shaft in a cantilever arrangement and having a working face and a facing off said working face, said wheel being formed with stroboscopic apertures through both said faces, a protective cover covering said grinding wheel toward the motor and on its periphery except for two segments of the wheel left free, which segments are at the front and bottom of the wheel, respectively, when said shaft is horizontal, said motor constituting means for rotating said grinding wheel at a speed suflicient to render visible through said apertures from the side of said grinding wheel where said face facing off said working face is disposed a workpiece when contacting said working face adjacent to either of said two segments, and means for directing a beam of light through said apertures onto said workpiece at the area contacting said working face for reflection by the workpiece toward the side of the wheel where said face facing off said working face is disposed, said last-mentioned means comprising two lamps each of which is fitted in said cover adjacent to one of said segments.

3. :In grinding apparatus, the combination of an electric motor having a shaft and arranged with freedom of pivotal movement on a horizontal axis normal to said shaft, means operable to lock said motor in any of at least two angular positions, in one of which said shaft is horizontal, a grinding wheel carried by said shaft in a 'ca'n'tilever arrangement and having a working face and a face facing off said working face, said wheel being formed with stroboscopic apertures through both said faces, a protective cover covering said grinding wheel toward the motor and on its periphery except for two segments of the wheel left free, which segments are at the front and bottom of the wheel, respectively, when said shaft is horizontal, said motor constituting means for rotating said grinding wheel at a speed sufiicient to render visible through said apertures from the side of said grinding Wheel where said face facing off said working face is disposed a workpiece when contacting said working face adjacent to either of said two segments, and means for directing a beam of light through said apertures onto said workpiece at the area contacting said working face for reflection by the workpiece toward the side of the wheel where said face facing off said working face is disposed, said last-mentioned means comprising two rod-type lamps fitted in said cover at right angles to each other adjacent to said two segments, respectively.

4. In grinding apparatus, the combination of an electric motor having a shaft and arranged with freedom of pivotal movement on a horizontal axis normal to said shaft, means operable to lock said motor in any of at least two angular positions, in one of which said shaft is horizontal, a grinding wheel carried by said shaft in a cantilever arrangement and having a working face and a face facing off said working face, said wheel being formed with stroboscopic apertures through both said faces, a protective cover covering said grinding wheel toward the motor and on its periphery except for two segments of the wheel left free, which segments are at the front and bottom of the wheel, respectively, when said shaft is horizontal, said cover being formed with two bores adjacent to said segments, respectively, which bores are at right angles to each other and have each a lateral opening facing said respective segment, two contacts, each of which is embedded in the bottom of one of said bores, two sleeves each of which is inserted in one of said bores and has a lateral opening in register with said opening in said bore and an end well having an aperture adjacent to said contact, said motor constituting means for rotating said grinding wheel at a speed sufficient to render visible through said apertures from the side of said grinding wheel where said face facing off said working face is disposed a workpiece when contacting said working face adjacent to either of said two segments, and means for directing a beam of light through said apertures onto said workpiece at the area contacting said working face for reflection by the workpiece toward the side of the wheel where said face facing off said working face is disposed, said lastmentioned means comprising two rod-type lamps, each of which is inserted in one of said sleeves and has at its end adjacent to said end wall of the sleeve a contact pin passing through said aperture in said end wall, each of 7 said lamps having a second terminal connected to ground, means resiliently engaging each of said lamps to urge said contact pins against said respective contacts, and means locking said lamps in said sleeves.

5. In a grinding apparatus, the combination of an electric motor having a shaft and being disposed with freedom of pivotal movement on a horizontal axis perpendicular to said shaft, means operable to lock said motor in any of at least two angular positions about said horizontal axis, including the position in which said shaft is vertical and the position in which said shaft is horizontal, said shaft having at least one extension from said motor and a grinding wheel carried on said extension in a cantilever arrangement, said grinding wheel having a working face and a face opposite said working face and being formed with stroboscopic apertures through both said faces, said motor constituting means for rotating said grinding Wheel at a speed suflicient to render visible through said apertures of said wheel, from the side having said face opposite its working face, a workpiece contacting said working face, and means for directing a beam of light through said apertures of the wheel onto the workpiece for reflection by the workpiece toward the side of the wheel having said face opposite said working face, said last-named means comprising at least one lamp disposed between said wheel and said motor, said lamp being secured for concurrent movement with said shaft, whereby it is in the same position relative to said wheel in every position of said shaft, said face opposite said working face being provided with a dull black finish between said apertures.

References Cited in the file of this patent UNITED STATES PATENTS 707,420 Hyde Aug. 19, 1902 1,700,634 Hopf Jan. 29, 1929 1,715,574 Skriba June 4, 1929 2,047,649 Robinson July 14, 1936 2,059,039 Sandman Oct. 27, 1936 2,070,734 Voegeli-Jaggi Feb. 16, 1937 2,087,012 Zimmerman July 13, 1937 2,231,900 Geoffrion Feb. 18, 1941 2,248,953 Bunch July 15, 1941 2,315,104 Bladenhofer Mar. 30, 1943 2,386,649 Belcourt Oct. 9, 1945 2,458,840 Eklund Jan. 11, 1949 FOREIGN PATENTS 523,879 Great Britain July 24, 1940 

